As cutting continues, growth will increase, the 

 rate depending largely upon the prevailng cutting 

 practice. If no significant change is made, it is 

 estimated that by 1966 depletion will exceed net 

 growth, not by the current ratio of 6 to 1 but by 

 about 2 to 1, owing to anticipated increase in in- 

 crement following conversion of mature stands to 

 net growth condition by cutting. If cutting took 

 the form of 50 percent selection of the most mature 

 trees in the stands logged, it is estimated that by 

 1966 depletion would exceed growth by only about 

 44 percent. 



Growth-depletion relationships vary widely for 

 the several units of the region (table 27 and fig. 

 25). In the Chelan-Colville and North Blue 

 Mountain units, total net growth will either about 

 equal or slightly exceed estimated depletion by 

 1966, depending on the quality of forestry practice. 

 In the Yakima River unit growth will be approach- 

 ing depletion. A substantial part of the net growth 

 in these three units, however, will be in nonpine 

 types of average low value and accessibility. In 

 the Yakima River unit more than half the forest 

 productive capacity is in these types. Even if all 

 possible improvement is made in cutting practice 

 there will still be a wide discrepancy between 

 ponderosa pine depletion and ponderosa pine 

 growth in 1966. But since total potential growth 

 exceeds assumed depletion by a wide margin in 

 each of these units, it would be possible, through 

 reasonably intensive forestry practice, eventually 

 to sustain an increased production if opportunity 

 to market species other than ponderosa pine is 

 developed. 



The average depletion assumed to occur in the 

 Deschutes River unit during the 30-year period 

 exceeds total potential growth by 15 percent — on 

 the pine sites alone by 37 percent. Potential 

 growth 1 cannot be attained here by the time the 

 existing mature timber will be gone, and hence a 

 material reduction in cut is inevitable. However, 



prompt and effective forest management can 

 mitigate the severity of the curtailment. The 

 excess of cut over permanent productive capacity 

 is even greater in the Bend area, the unit's prin- 

 cipal industrial center, than it is for the unit as a 

 whole. The area tributary to Bend has been so 

 badly overcut for several decades that drastic 

 reduction in output will be unavoidable in less 

 than two decades. 



In the South Blue Mountain unit, assumed 

 average depletion for the period 1936-65 is 76 

 percent of the potential growth of the ponderosa 

 pine sites. Properly managed, the timber resources 

 are sufficient to prevent serious interruption of 

 production for the unit as a whole, if the cut does 

 not advance beyond that assumed. Local short- 

 ages, however, already exist in this unit and may 

 be expected to increase in severity. 



The Klamath Plateau unit includes the principal 

 lumber-producing center in the region, Klamath 

 Falls, and is assumed to yield more than 36 percent 

 of the region's cut for the next three decades. If 

 this heavy cutting actually occurs, a drastic future 

 reduction is inevitable. Necessary curtailment 

 will be less severe if cutting is made under good 

 forestry practice, but even so there will be a large 

 deficit between anticipated growth and depletion 

 as of 1966 (fig. 22). Since assumed average deple- 

 tion for the period 1936-65 exceeds total potential 

 growth by 36 percent, it is evident that production 

 could not be maintained at that level, even though 

 all the unit's timberlands had been under reasona- 

 bly intensive forestry management for many years. 

 The longer the inevitable curtailment is postponed 

 the more severe it will eventually be. 



These assumptions of heavy depletion for the 

 period 1936-65, although justified by present 

 trends, most decidedly are not recommendations. 

 In the Deschutes River and Klamath Plateau 

 units particularly, every constructive effort should 

 be made to alter current depletion trends. 



52 



